1. A torsion bar is a spring that is a long, round, hardened steel bar similar to a coil spring except that it is a straight bar. Continued Figure 85–26 A torsion bar resists twisting and is used as a spring on some cars and many four-wheel-drive pickup trucks and sport utility vehicles. The larger the diameter, or the shorter the torsion bar, the stiffer the bar.

2. A steering knuckle serves two purposes: To join the suspension to the wheel To provide pivot points between the suspension and the wheel Continued The only steering knuckle that uses a kingpin is on an I-beam or twin I-beam front suspension.

3. A control arm is a suspension link that connects a knuckle or wheel flange to the frame. Continued Figure 85–33 Control arms are used to connect the steering knuckle to the frame or body of the vehicle and provide the structural support for the suspension system. One end of a control arm attaches to the knuckle or wheel flange, with either a ball joint or bushing. The opposite end attached to a frame member, pivots on a bushing. It pivots to allow the axle or knuckle vertical travel.

4. Ball joints are ball-and-socket joints, similar to the joints in a person’s shoulder. They allow the front wheels to move up and down, as well as side to side (for steering). A vehicle can be equipped with coil springs, mounted either above the upper control arm or on the lower control arm. Continued Figure 85–34a Ball joints provide the freedom of movement necessary for steering and suspension movements.

5. The type used is determined by the design engineer, the tech cannot change the type of ball joint used for a particular application. The load-carrying (weight-carrying) ball joint is subjected to the greatest amount of wear and is most frequently replaced.

6. Most cars and trucks are equipped with a stabilizer bar on the front suspension, a round, hardened steel bar (usually SAE 4560 or 4340 steel) attached to both lower control arms with bolts and rubber bushing washers called stabilizer bar bushings. See Figure 85–40. Continued A stabilizer bar is also called an anti-sway bar (sway bar) or anti- roll bar (roll bar). A stabilizer bar operates by twisting the bar if one side of the vehicle moves up or down in relation to the other side, such as during cornering, hitting bumps, or driving over uneven road surfaces. See Figure 85–41.

7. Continued

12. Shock absorbers are used on all conventional suspension systems to dampen and control the motion of the vehicle’s springs. Without shock absorbers (dampers), the vehicle would continue to bounce after hitting bumps. See Figure 85–44. Continued

14. Most shock absorbers are direct acting because they are connected directly between the vehicle frame or body and the axles. Continued

15. What Are Remote Reservoir Shocks? Remote reservoir shock absorbers are units designed for heavy-duty use that use a separate container for the working fluid. The purpose of the remote fluid reservoir is to keep the temperature of the fluid stable, which helps the shock provide consistent dampening under all conditions. Figure 85–50 The shock absorber is on the right and the fluid reservoir for the shock is on the left.

16. Air Springs Some electronically controlled suspension systems use air springs. A basic air spring consists of a rubber air chamber, generally closed at the bottom by a piston fitted into a control arm, or by a strut shock absorber. Electronically controlled suspension systems that use air springs as the only springs are available on some Hummer, and many Ford, Mercury and Lincoln vehicles. See Figures 85–52 Continued

18. Some air springs are in effect auxiliary springs inside a coil-spring strut. In these designs, the coil spring supports the weight of the vehicle, while the air spring raises or lowers the body to adjust ride height according to load. Continued

19. Coil-Over Shocks A coil-over shock absorber uses an external coil spring to boost the performance of the basic shock absorber. The spring usually extends from the upper shock mount to a seat on the lower portion of the cylinder. The spring rate added to the hydraulic resistance makes the shock stiffer. Continued

20. A strut is a sturdy shock absorber that is also a structural component of the suspension. A strut is a suspension link as well as a shock absorber. The casing of a strut must be strong and rigid to function as a suspension link. The shock absorber assembles inside the casing of a strut, and may be either a removable cartridge or an integral part of the strut. Continued

21. A Strut Bar is a performance modification that helps eliminate/ reduce body roll Continued

22. MacPherson Struts The MacPherson strut, named after Earle S. MacPherson, who developed the suspension design in the late 1940s and patented it in 1953, is the most commonly used type. A MacPherson strut includes the suspension spring—a coil spring that surrounds the strut casing— so that it transfers weight of the body to the wheel. Continued

23. Helps to keep tires from hopping Keeps body from bouncing after bumps Filled with oil and a gas

24. Tire wear Chapter 14 © 2007 Rolling Hills Publishing www.AutoUpkeep.com 24

25. Tire Wear Indicator Bars Set at 2/32nds of an inch (1.6 mm) Chapter 14 © 2007 Rolling Hills Publishing www.AutoUpkeep.com 25

32. Tire Rotation Chapter 14 © 2007 Rolling Hills Publishing www.AutoUpkeep.com 32

33. Lubricate steering and suspension parts? Check power steering fluid Check/change power steering belt Check tires for abnormal wear Check shocks/struts Check parts for wear